Осуществите превращения C2h6-c2h5Br-C7h16--c7h15cl
C2H6 + Br2 = C2H5Br + HBr C2H5Br + C5H11Br + 2Na = C7H16 + 2NaBr C7H16 + Cl2 = C7H15Cl + HCl